Switched-mode circuits, including switched-mode power supplies and motor controllers, are pervasive in many electronic applications from computers to automobiles. Generally, voltages within a switched-mode power supply system are generated by performing a DC-DC, DC-AC, and/or AC-DC conversion by operating a switch coupled to an inductor or a transformer. Switched-mode power supplies are usually more efficient than other types of power conversion systems because power conversion is performed by controlled charging and discharging a low loss component, such as an inductor or transformer, therefore reducing energy lost due to power dissipation across resistive voltage drops. Similarly, switched-mode motor controllers may be used to efficiently commutate DC brushless motors with low losses in the driving circuitry.
Over the past few years, there has been increasing market pressure to both lower the cost and increase the power efficiency of switch-mode power supplies. For example, in low-power consumer products such as portable computers and smartphones, smaller, more efficient power supplies allow for longer battery life. Higher efficiencies also allow for smaller, more portable packaging that needs less heat sinking.
Generally, increasing the efficiency of a switched-mode power supply involves the reduction of power loss during the operation of the converter. Common causes of power loss in a switched-mode power supply include transistor switching losses, resistive losses in passive components, and core losses in the magnetic components. By addressing these losses, efficiency can be improved.